MDEV-12672 Replicated TIMESTAMP fields given wrong value near DST change

Implement a special Copy_field method for timestamps, that copies
timestamps without converting them to MYSQL_TIME (the conversion
is lossy around DST change dates).

mysql-test/r/old-mode.result

@@ -127,3 +127,26 @@ Warning	1264	Out of range value for column 'a' at row 1
 Warning	1264	Out of range value for column 'b' at row 1
 DROP TABLE t1;
 SET @@global.mysql56_temporal_format=DEFAULT;
+set time_zone='Europe/Moscow';
+set global mysql56_temporal_format=false;
+create table t1 (a timestamp);
+set timestamp=1288477526;
+insert t1 values (null);
+set timestamp=1288481126;
+insert t1 values (null);
+select a, unix_timestamp(a) from t1;
+a	unix_timestamp(a)
+2010-10-31 02:25:26	1288477526
+2010-10-31 02:25:26	1288481126
+set global mysql56_temporal_format=true;
+select a, unix_timestamp(a) from t1;
+a	unix_timestamp(a)
+2010-10-31 02:25:26	1288477526
+2010-10-31 02:25:26	1288481126
+alter table t1 modify a timestamp;
+select a, unix_timestamp(a) from t1;
+a	unix_timestamp(a)
+2010-10-31 02:25:26	1288477526
+2010-10-31 02:25:26	1288481126
+drop table t1;
+set time_zone=DEFAULT;

mysql-test/suite/rpl/r/rpl_temporal_format_mariadb53_to_mysql56_dst.result

+include/master-slave.inc
+[connection master]
+set global time_zone='Europe/Moscow';
+set time_zone='UTC';
+stop slave;
+start slave;
+set global mysql56_temporal_format=false;
+set global time_zone='Europe/Moscow';
+set time_zone='UTC';
+create table t1 (pk int primary key, t timestamp not null);
+set timestamp = 1288477526;
+insert into t1 values (1,null);
+set timestamp = 1288481126;
+insert into t1 values (2,null);
+select pk, t, unix_timestamp(t) from t1;
+pk	t	unix_timestamp(t)
+1	2010-10-30 22:25:26	1288477526
+2	2010-10-30 23:25:26	1288481126
+set time_zone=default;
+select pk, t, unix_timestamp(t) from t1;
+pk	t	unix_timestamp(t)
+1	2010-10-31 02:25:26	1288477526
+2	2010-10-31 02:25:26	1288481126
+set global time_zone=default;
+drop table t1;
+set global time_zone=default;
+set global mysql56_temporal_format=default;
+include/rpl_end.inc

mysql-test/suite/rpl/t/rpl_temporal_format_mariadb53_to_mysql56_dst.test

+#
+# MDEV-12672 Replicated TIMESTAMP fields given wrong value near DST change
+#
+source include/have_binlog_format_row.inc;
+source include/master-slave.inc;
+
+connection slave;
+set global time_zone='Europe/Moscow';
+set time_zone='UTC';
+stop slave;
+start slave;
+
+connection master;
+set global mysql56_temporal_format=false;
+set global time_zone='Europe/Moscow';
+set time_zone='UTC';
+
+create table t1 (pk int primary key, t timestamp not null);
+set timestamp = 1288477526;
+insert into t1 values (1,null);
+set timestamp = 1288481126;
+insert into t1 values (2,null);
+
+sync_slave_with_master;
+
+select pk, t, unix_timestamp(t) from t1;
+set time_zone=default;
+select pk, t, unix_timestamp(t) from t1;
+
+set global time_zone=default;
+
+connection master;
+drop table t1;
+set global time_zone=default;
+set global mysql56_temporal_format=default;
+
+source include/rpl_end.inc;

mysql-test/t/old-mode.test

@@ -83,3 +83,20 @@ SELECT TO_DAYS(a), TO_DAYS(b) FROM t1;
 DROP TABLE t1;
 SET @@global.mysql56_temporal_format=DEFAULT;
 
+#
+# MDEV-12672 Replicated TIMESTAMP fields given wrong value near DST change
+#
+set time_zone='Europe/Moscow';
+set global mysql56_temporal_format=false;
+create table t1 (a timestamp);
+set timestamp=1288477526;
+insert t1 values (null);
+set timestamp=1288481126;
+insert t1 values (null);
+select a, unix_timestamp(a) from t1;
+set global mysql56_temporal_format=true;
+select a, unix_timestamp(a) from t1;
+alter table t1 modify a timestamp;
+select a, unix_timestamp(a) from t1;
+drop table t1;
+set time_zone=DEFAULT;

sql/field_conv.cc

@@ -417,6 +417,18 @@ static void do_field_decimal(Copy_field *copy)
 }
 
 
+static void do_field_timestamp(Copy_field *copy)
+{
+  DBUG_ASSERT(copy->from_field->type() == MYSQL_TYPE_TIMESTAMP);
+  DBUG_ASSERT(copy->to_field->type() == MYSQL_TYPE_TIMESTAMP);
+  ulong sec_part;
+  Field_timestamp *f= static_cast<Field_timestamp*>(copy->from_field);
+  Field_timestamp *t= static_cast<Field_timestamp*>(copy->to_field);
+  my_time_t ts= f->get_timestamp(&sec_part);
+  t->store_TIME(ts, sec_part);
+}
+
+
 static void do_field_temporal(Copy_field *copy)
 {
   MYSQL_TIME ltime;
@@ -724,7 +736,9 @@ Copy_field::get_copy_func(Field *to,Field *from)
           ((to->table->in_use->variables.sql_mode &
             (MODE_NO_ZERO_IN_DATE | MODE_NO_ZERO_DATE)) &&
              mysql_type_to_time_type(to->type()) != MYSQL_TIMESTAMP_TIME))
-        return do_field_temporal;
+        return (from->type() == MYSQL_TYPE_TIMESTAMP &&
+                to->type() == MYSQL_TYPE_TIMESTAMP)
+                ? do_field_timestamp : do_field_temporal;
       /* Do binary copy */
     }
     // Check if identical fields